DXU 2014 Visalia K9LA

Report
DX University
Visalia California – 2014
DX University – Visalia 201
2014
Propagation for Working DX
Carl Luetzelschwab K9LA
Carl Luetzelschwab K9LA
DX University – Visalia 201
2014
Carl was licensed as WN9AVT in October
1961. He selected K9LA in 1977 when the FCC
offered 1 x 2 call signs to Extra Class licensees.
Carl enjoys propagation, DXing, contesting (he
was the Editor of The National Contest Journal
from 2002-2007), antennas and vintage rigs.
He earned a BSEE and MSEE from Purdue
University, and retired in late 2013 as an RF
design engineer with Motorola (1974-1988) and
Raytheon (1988-2013).
Carl is a card checker for both ARRL and CQ
awards, is at the Top of the DXCC Honor Roll,
and enjoys viewing old QSLs (especially from
deleted entities).
WN9AVT/WA9AVT
Propagation for Working DX
DX University – Visalia 201
2014
• In this presentation I will address three issues
• When is the best time to work the DX station?
• Which way should I point my antenna?
• What should I do when propagation is disturbed?
• References for your home library
• Robert Brown NM7M (SK) “The Little Pistol’s Guide to HF
Propagation” - available at http://k9la.us – moderate reading
• The NEW Short Wave Propagation Handbook (W3ASK-N4XXK6GKU, CQ, 1995) – light reading
• Radio Amateurs Guide to the Ionosphere (Leo McNamara, Krieger
Publishing, 1994) – moderate reading
• Ionospheric Radio (Kenneth Davies, Peter Peregrinus Ltd, 1990) –
heavy reading
• Visit http://k9la.us – timely topics, basic concepts, tutorials,
general, 160m, HF, VHF, contesting and webinars on propagation
Propagation for Working DX – Best Time
DX University – Visalia 201
2014
When is the best time to work the DX station?
• HF propagation is due to refraction in the ionosphere
• The ionosphere varies considerably
• Amount of ionization varies by latitude
• Highest MUFs at low latitudes (around the equator)
• Lowest MUFs at high latitudes (polar regions)
• Most of us are in between those two extremes
• Amount of ionization varies over time
• Long-term – over a solar cycle
• Mid-term – throughout the seasons
• Short-term – throughout the day and even day-to-day
• And then there are anomalies!
Propagation for Working DX – Best Time
DX University – Visalia 201
2014
• Ionosphere varies over a solar cycle
• Approximately 11 years from min to max
• Cycle 24 is
• Higher bands (15/12/10) depend on ionization (MUF) the lowest in
best at solar max – where we are now – during day
our lifetimes
• Lower bands (160/80/40) depend on ionospheric
absorption – generally best at solar min – during night • Fortunately it
is exhibiting
• Mid bands (30/20/17) hold up throughout solar cycle
a second
peak right
now
• Second peak
higher than
first peak
• Higher bands
in great
shape now
Propagation for Working DX – Best Time
DX University – Visalia 201
2014
Higher bands and 6-Meters
The Big Picture – SFI, SSN, Ap
• Needed ‘long-term’ solar flux or
sunspot number for F2 openings
– 6-Meters: SFI > 200 or ssn > 100
– 10-Meters: SFI > 100 or ssn > 50
– 12-Meters: SFI > 75 or ssn > 35
– 15-Meters: SFI > 50 or ssn > 25
All bands
– Ap index less than 7 indicates
quiet geomagnetic field
– Over the pole paths (high latitude)
are best
http://www.solen.info/solar/
Propagation for Working DX – Best Time
DX University – Visalia 201
2014
• Ionosphere varies throughout the seasons
• Composition of the atmosphere changes throughout the year
• More F2 region ionization targets (atomic oxygen) in the fall,
winter and spring months in the northern hemisphere generally
results in higher MUFs in these months
Propagation for Working DX – Best Time
DX University – Visalia 201
2014
• Ionosphere varies throughout the day
• The MUF maximizes during the day and minimizes during the
night – but not the same values on consecutive days
• Anomalies in the ionosphere
• For example, there are three areas in the world where the MUF
maximizes during the night
• Around Japan, off the northeast coast of North America and over
the Weddell Sea near Antarctica
• So how do you make sense of all this variability?
• On the lower bands, the best times are when the path is in
darkness – especially around sunrise/sunset times
• On the higher bands, the best times are when the path is
mostly in daylight – in other words, point your antenna
towards the Sun
Propagation for Working DX – Best Time
DX University – Visalia 201
2014
For more specific predictions . . .
• Propagation prediction software packages available
• For example, two free ones are
• VOACAP
• Voice of America’s version of IONCAP
• W6ELProp
• More user friendly than VOACAP
• Has a very useful mapping application that includes
great circle paths and the terminator so you can see how
your RF gets from Point A to Point B
• Tutorials for these two are available at http://k9la.us
• Includes download instructions, set up instructions and
interpretation of results
Propagation for Working DX – Best Time
DX University – Visalia 201
2014
• If you don’t want to roll your own . . .
• Use the predictions by N6BV
• Over 240 locations worldwide
Predictions from any
pin to any other pin
• Over six phases of a solar cycle
• Summary predictions to seven continental areas (EU, FE, SA,
AF, AS, OC, NA) on 80m, 40m, 20m, 15m, 10m
• Detailed predictions to all forty CQ zones on 160m – 10m
(including 30m, 17m and 12m)
• http://radio-ware.com/books/N6BV.html
Propagation for Working DX – Which Way
DX University – Visalia 201
2014
Which way should I point my antenna?
• Purpose of an antenna is to put the most energy
• at the required azimuth angle (N, NE, E, etc)
• at the required elevation angle (10o, 20o, etc)
• with the required polarization (horizontal, vertical, circular)
• The ionosphere dictates these three parameters
• Biggest misconception may be that the higher the antenna, the
lower the ‘radiation angle’ and thus the better the signal strength
• But the ionosphere determines the elevation angle that gets
from Point A to Point B, not the antenna
• At times a higher angle is best
Propagation for Working DX – Which Way (azimuth)
DX University – Visalia 201
2014
• An electromagnetic wave travels in a
straight line unless it is refracted,
reflected, or scattered
• Shortest distance between two points
on a globe is a great circle path
• This is short path - airliners generally
fly short great circle paths to use the
minimum amount of fuel (exceptions
due to storms, winds, etc)
ANTIPODE
• Other way around is long path
• Location on opposite side of Earth to
your location is called your antipode
• Short path and long path are equal –
approx 20,000 km (12,500 miles)
Most of the time short path is
best – sometimes long path
is better – at other times gray
line is best
Propagation for Working DX – Which Way (azimuth)
DX University – Visalia 201
2014
• Most of the time a great circle path is dictated
• Skewed paths and scatter paths sometimes available
• Use W6ELProp mapping feature to see the great
circle paths (and the terminator)
• With respect to polarization, circular polarization is
predominant on the higher HF bands
• Horizontal or vertical equally good
• Only down 3 dB if the gains are the same
• Preference is horizontal antenna
• Vertical antenna picks up more man-made noise and is more
ground dependent
Propagation for Working DX – Which Way (azimuth)
DX University – Visalia 201
2014
Example: W6 to EU on 75-Meter LP via gray line
• Generally occurs from
November thru March
• Around W6 sunrise
• Good signal strengths
without high power
levels and without big
antennas
• Example shown is
classical “gray line”
propagation
Good example of the mapping
application in W6ELProp
Propagation for Working DX – Which Way (az)
DX University – Visalia 201
2014
Example: 10-Meter LP for North America
factor
solar activity
month
sunrise end of path
sunset end of path
headings
condition
smoothed 10.7 cm solar flux > about 120
smoothed sunspot number > about 70
mostly March thru September
first F2 hop in daylight
not later than about 4 hours after sunset
in the morning: southeast through south
in the evening: south through southwest
For W6, evening long
path to EU is probably
most productive
Propagation for Working DX – Which Way (elevation)
DX University – Visalia 201
2014
Elevation angles required on 10-Meters for Indianapolis
EU
JA
AF
SE Asia
OC
SA
USA
30
25
percetn of the time
20
15
10
5
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
elevation angle, degrees
• Indianapolis to the world by continent (including USA) on 10-Meters
• N6BV data on the CD-ROM in the 2012 ARRL Antenna Book (22nd Edition)
Propagation for Working DX – Which Way (elevation)
DX University – Visalia 201
2014
Antenna elevation patterns
5-el a t 25 ft
5-el a t 50 ft
5-el a t 100 ft
20
perc etn of the time or g ain in
dB i
15
10
5
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
elev atio n an g le, d eg rees
5-element HyGain monobander over average ground
Propagation for Working DX – Which Way (elevation)
DX University – Visalia 201
2014
Superimpose required elevation angles on antenna patterns
all elevation angles
5-el at 25 ft
5-el at 50 ft
5-el at 100 ft
percetn of the time or gain in dBi
20.0
• Data available on
other bands
• To cover all the
elevation angles,
probably need
stack of antennas
15.0
10.0
5.0
0.0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
• Tough to achieve
low angle
radiation on low
bands
elevation angle, degrees
• At 25 ft (red) – doesn’t cover the low angles (< 10o) very well
• At 100 ft (purple) – covers the low angles, but has two nulls at 10o and 20o
• At 50 ft (blue) – probably the best height overall for a single Yagi – 1.5 λ
Propagation for Working DX – Disturbances
DX University – Visalia 201
2014
The Big Picture – Disturbances to Propagation
• Review summary conditions at http://www.swpc.noaa.gov/
• G = Geomagnetic storm - disturbance in the Earth’s magnetic field
caused by gusts in the solar wind that blow by Earth (CMEs and coronal
holes)
• S = Solar radiation storm – disturbance in the polar cap due to increased
levels of energetic protons
• R = Radio blackout – disturbance on the daylight side of Earth due to
increased electromagnetic radiation at X-ray wavelengths
• Each is on a scale of 1 (minor) to 5 (extreme)
• More details at http://www.swpc.noaa.gov/NOAAscales/
Propagation for Working DX – Disturbances
DX University – Visalia 201
2014
Disturbances to Propagation
– A Visual Picture
1a) Geomagnetic
storm – decreased
F2 region MUFs at
high and mid
latitudes both day
and night
X
2) Solar radiation
storm (a.k.a.
PCA) – increased
D region
absorption in the
polar cap due to
energetic protons
from a big solar
flare
North magnetic pole
3) Radio blackout –
increased absorption on
daylight side of Earth due
to extremely short
wavelength
electromagnetic radiation
from a big solar flare
1b) Geomagnetic
storm – increased
auroral ionization
causing increased
absorption and
horizontal refraction
(skewed path)
Propagation for Working DX – Disturbances
DX University – Visalia 201
2014
What can you do to mitigate a disturbance?
• Geomagnetic storm – effect can last up to a week
• Check for auroral propagation at VHF
• Check for skewed paths on 160m
• Move down in frequency on HF paths thru mid and high latitudes
• Look for enhanced low latitude paths (e.g., southern USA to VK/ZL)
• Solar radiation storm – effect can last up to several days
• For paths over the poles, try long path if the short path is degraded
and vice versa (since the effect is not necessarily similar in the north
and south polar caps)
• Radio blackout – effect can last up to several hours
• Move to the higher frequencies
• Use paths that are in darkness
Propagation for Working DX – Summary
DX University – Visalia 201
2014
• When is the best time to work the DX station?
• Lower bands – solar min, night, special attention around sr/ss
• Higher bands – solar max, path mostly in daylight (can tolerate some
darkness)
• Use propagation predictions to pin down more specific times
• Which way should I point my antenna?
• Use propagation predictions and mapping feature to identify short
path, long path and gray line path
• Short great circle path best most of the time
• Need to cover the required elevation angles
• Polarization is an issue on 160-meters
• What should I do when propagation is disturbed?
• Try the suggestions on the previous slide – no guarantees!
• Read, read, read to understand more

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